Results Of Human Subject Experiments Research Articles

Occupant Feedback and Control Behavior with a Newly Developed Personalized Environmental Control System (PECS)

Personalized Environmental Control Systems (PECS) allow control over indoor environmental quality (IEQ) parameters of the microclimate around individual occupants. The present study reports on the results of human subject experiments evaluating a prototype of PECS. The tested prototype had heating, cooling, and ventilation (air circulation through a filter and an ultraviolet germicidal irradiation component) functions. The objective of the present experiment was to obtain the occupants' subjective responses and physiological parameters such as skin temperature, with and without the use of PECS. The occupants' interaction with the PECS prototype was also observed. Experiments were conducted with 24 university students (12 male and 12 female subjects) over a 5-week period between February and March 2022. Different ambient temperature settings between 18 and 28 °C were tested each week. In each week, subjects participated in two 3-hour sessions, once with PECS and once without it. Subjects with PECS were able to adjust the PECS functions freely throughout the measurements, and the changes they made were recorded in an internal log of the PECS. Subjective responses such as thermal sensation and acceptability were compared with their PECS operation to evaluate the effect of PECS, together with each occupant’s interaction with PECS.

Exposure to oxybenzone from sunscreens: daily transdermal uptake estimation.

Fugacity, the driving force for transdermal uptake of chemicals, can be difficult to predict based only on the composition of complex, non-ideal mixtures such as personal care products. Compare the predicted transdermal uptake of benzophenone-3 (BP-3) from sunscreen lotions, based on direct measurements of BP-3 fugacity in those products, to results of human subject experiments. We measured fugacity relative to pure BP-3, for commercial sunscreens and laboratory mixtures, using a previously developed/solid-phase microextraction (SPME) method. The measured fugacity was combined with a transdermal uptake model to simulate urinary excretion rates of BP-3 resulting from sunscreen use. The model simulations were based on the reported conditions of four previously published human subject studies, accounting for area applied, time applied, showering and other factors. The fugacities of commercial lotions containing 3-6% w/w BP-3 were ~20% of the supercooled liquid vapor pressure. Simulated dermal uptake, based on these fugacities, are within a factor of 3 of the mean results reported from two human-subject studies. However, the model significantly underpredicts total excreted mass from two other human-subject studies. This discrepancy may be due to limitations in model inputs, such as fugacity of BP-3 in lotions used in those studies. The results suggest that combining measured fugacity with such a model may provide order-of-magnitude accurate predictions of transdermal uptake of BP-3 from daily application of sunscreen products.

Personalised and dynamic image precompensation for computer users with ocular aberrations

Most of the computer users with ocular aberrations such as myopia, hyperopia and other high-order aberrations are subject to visual blurring, which may impede the efficient interactions with the computers. Conventional methods used to counter visual blurring include spectacles and contact lenses. In this paper, we introduce an image preprocessing method that is designed to counteract the visual blurring caused by the aberration of the eye. In this method, the presented images are preprocessed by performing personalised compensation according to the ocular aberration of the computer user. In order to overcome the mismatch between the aberration used to generate the precompensation and the actual aberrations at the time of viewing, dynamic ocular aberrations are derived from the resizing of the initial aberration data measured by the wavefront analyzer. The dynamic ocular aberrations are used to update the image precompensation in real time. Results of human subject experiment show that the image recognition accuracy was significantly increased after the dynamic precompensation was applied. Subjective impressions from the participants confirmed the effectiveness of the method.

Validation of the Fiala multi-node thermophysiological model for UTCI application

The important requirement that COST Action 730 demanded of the physiological model to be used for the Universal Thermal Climate Index (UTCI) was its capability of accurate simulation of human thermophysiological responses across a wide range of relevant environmental conditions, such as conditions corresponding to the selection of all habitable climates and their seasonal changes, and transient conditions representing the temporal variation of outdoor conditions. In the first part of this study, available heat budget/two-node models and multi-node thermophysiological models were evaluated by direct comparison over a wide spectrum of climatic conditions. The UTCI-Fiala model predicted most reliably the average human thermal response, as shown by least deviations from physiologically plausible responses when compared to other models. In the second part of the study, this model was subjected to extensive validation using the results of human subject experiments for a range of relevant (steady-state and transient) environmental conditions. The UTCI-Fiala multi-node model proved its ability to predict adequately the human physiological response for a variety of moderate and extreme conditions represented in the COST 730 database. The mean skin and core temperatures were predicted with average root-mean-square deviations of 1.35 ± 1.00°C and 0.32 ± 0.20°C, respectively.

Prediction of human thermophysiological responses during shower bathing

This study develops a model to predict the thermophysiological response of the human body during shower bathing. Despite the needs for the quantitative evaluation of human body response during bathing for thermal comfort and safety, the complicated mechanisms of heat transfer at the skin surface, especially during shower bathing, have disturbed the development of adequate models. In this study, an initial modeling approach is proposed by developing a simple heat transfer model at the skin surface during shower bathing applied to Stolwijk's human thermal model. The main feature of the model is the division of the skin surface into three parts: a dry part, a wet part without water flow, and a wet part with water flow. The area ratio of each part is decided by a simple formula developed from a geometrical approach based on the shape of the Stolwijk's human thermal model. At the same time, the convective heat transfer coefficient between the skin and the flowing water is determined experimentally. The proposed model is validated by a comparison with the results of human subject experiments under controlled and free shower conditions. The model predicts the mean skin temperature during shower fairly well both for controlled and free shower bathing styles.

Virtual Training via Vibrotactile Arrays

What is often missing from many virtual worlds and training simulations is a physical sense of the confinement and constraint of the virtual environment. We present a method for providing localized cutaneous vibratory feedback to the user's right arm. We created a sleeve of tactors linked to a real-time human model; the tactors activate to apply sensation to the corresponding body area. The hypothesis is that vibrotactile feedback to body areas provides the wearer sufficient guidance to assume correct body configurations and ascertain the existence and physical realism of access paths. We present the results of human subject experiments that study both explicit and implicit training of skills using vibrotactile arrays. Implicitly, collision awareness is achieved by activating the appropriate tactor when a body part collides with the scene; thus, the user will attempt to correct his or her body configuration. Explicitly, we use the tactors to guide the body into the proper configuration. The results of human subject experiments clearly show that the use of full arm vibrotactile feedback improves performance over purely visual feedback for navigating the virtual environment, as well as allowing easy acquisition of new skills. These results validate the empirical performance of this concept.